How Long Does It Take to Relax? Observation of Driver Behavior During Real-World Conditionally Automated Driving

Conditionally Automated Driving (CAD) may reduce drivers’ mental load and provide the driver opportunities to engage in non-driving related tasks (NDRTs). Such systems can be expected to enter the market within the next few years and effects of automated driving need to be better understood first to maximize their potential benefit. A road-traffic study with N = 41 subjects was conducted using a Wizard-of-Oz vehicle to simulate CAD. We observed driver behavior during the initial use of CAD and set out to answer the question: How long does it take to relax? Gaze behavior, seating position, NDRT and self-reported feedback helped in identifying the phases of initial contact and familiarization. The results showed that loose seating position, glance off the road, NDRT engagement and self-reports indicate a familiarization after 10 min of total CAD and correlated with gender and previous experience with advanced driver assistance systems (ADAS). No significant connection was found between subjective and objective data.